The aim of this study was to profile and compare blood naltrexone and 6-beta-naltrexol levels with time following treatment with two sustained-release naltrexone preparations produced by GoMedical Industries, Australia at a community heroin treatment clinic in Perth, Western Australia. A sample of 10 patients who each received a 1.7 g naltrexone implant were compared to 24 patients who each received a 3.4 g naltrexone implant as treatment for heroin dependence. Blood naltrexone levels following treatment with the 1.7 g naltrexone implant remained above 2 and 1 ng/ml for approximately 90 and 136 days, respectively. Use of the 3.4 g naltrexone implant extended the period of coverage to approximately 297 (1 ng/ml) or 188 (2 ng/ml) days. Blood 6-beta-naltrexol levels remained above 10 ng/ml for approximately 18 and 83 days, respectively, following use of the 1.7 g and 3.4 g naltrexone implants. The current study data indicate that blood naltrexone and 6-beta-naltrexol levels following treatment with either the 1.7 g or 3.4 g naltrexone implant are greater than those reported in other published data on other sustained-release naltrexone preparations. Furthermore, duration of blood naltrexone and 6-beta-naltrexol levels achieved following use of the 3.4 g implant were superior to those achieved with the 1.7 g naltrexone implant, with naltrexone blood levels maintained above 2 ng/ml for a period of approximately 6.3 months compared to 3 months, respectively. The implications of this in managing the heroin-dependent patient, especially those who find it difficult to shift away from dependent use patterns, are discussed.

Our group and others internationally have previously reported data on the use of low-dose flumazenil administered intravenously for the management of benzodiazepine withdrawal. This paper describes the first reported use of subcutaneous flumazenil infusion in the management of acute benzodiazepine withdrawal. Self-reported withdrawal symptoms and psychological state and anxiety sequelae were collected at baseline and then at intervals to 5 days following initiation of subcutaneous flumazenil infusion. Data indicate that patient subjective benzodiazepine withdrawal symptoms were well managed, with significant reduction in psychological distress seen over the duration of treatment. Perceived difficulty in performing everyday functions was positively correlated with withdrawal severity and improved over treatment. Patients reported high treatment comfort, willingness to undertake a future subsequent treatment using this technique, and willingness to recommend this treatment to a friend. This small proof-of-concept study indicates that subcutaneous flumazenil infusion has excellent tolerability, efficacy and improvement on measures of psychological distress. Given this technique is less invasive and requires fewer staff resources compared with intravenous administration, it may prove a significant asset in the management of benzodiazepine withdrawal.

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This case series provides preliminary evidence that the pregnant heroin user can be managed by naltrexone implant without obvious risk to the mother or developing foetus. Importantly, the current case series suggests that the pregnant woman who finds it difficult to stabilise on oral naltrexone maintenance and returns to dependent heroin use may be managed using implantable naltrexone, thereby removing from her the onus for daily naltrexone medication compliance. The authors conclude that naltrexone implant may represent an important procedure for managing the pregnant heroin dependent patient who finds it difficult to shift away from her heroin use patterns. These preliminary findings require confirmation using a much larger controlled study.